A Tyneside chemicals expert is warning that civilians caught in a terrorist attack may not be given vital antidotes quickly enough.

Prof Peter Blain of Newcastle University has told the Government it would be much more difficult to protect civilians than the armed forces, who are prepared for an attack.

Prof Blain, who is heading a Government advisory committee, says it could take more than half an hour for people caught in an attack to be treated - but nerve agents can have serious effects within minutes.

He said: "It might take more than 30 minutes for emergency services to arrive and administer antidotes.

"There are treatments for the toxic effects of some nerve gases, such as sarin and other potential terrorist weapons, but these must be given as quickly as possible after poisoning to be effective."

The Blain Committee report states: "There must be urgent research towards establishing rapid reaction times within which oxygen and other breathing aids can be provided.

"However it is appreciated that providing such assistance in a mass-casualty situation will be difficult and these difficulties may be added to by the need to decontaminate patients before hospitalisation.

"Unless ambulances routinely carry antidotes, it is difficult to foresee circumstances in which pre-hospital administration is likely to occur."

The Government is recommending that the NHS stockpiles "ComboPens", which contain a cocktail of antidote suitable for injection into muscles. These syringes are already issued to the armed forces.

The Department of Health indicated that it already had some supplies of ComboPens and said it was carefully considering the recommendations.

It declined to give details on the grounds that such information might help terrorists.

The Government recently drew up contingency plans relating to smallpox and has inoculated key workers.